1. Field of the Invention
The present invention relates to an ink jet recording apparatus to form a desired image by discharging ink and a mechanism for discharging maintenance and recovery employed to maintain and recover the discharging condition of recording means of discharging ink for the recording apparatus.
2. Related Background Art
In an ink jet recording apparatus, there is a phenomenon observed when the ink mist generated by a recording performance adheres to the discharging port formation face of the recording head or that dirt and dust in the apparatus or foreign substances such as paper particles, etc. concomitantly produced when transporting a recording medium, adhere to the discharging port formation face. Such adherence of foreign substances to the discharging port formation face results in shifting the emitting direction of ink in some cases or clogging the discharging ports in the worst case. This leads to the deterioration of the ink discharging condition such as clogging, etc. and lowers the quality of the recorded image. For the purpose of improving such condition causing the deterioration of image quality, there has been proposed an apparatus wherein a cleaning member is arranged at a position in the non-recording region of a recording area opposite to the discharging port formation face to remove the adherent ink and foreign substances by slidably rubbing the discharging port formation face with a blade made of silicone rubber, etc., for example. Also, there has been proposed an apparatus provided with means for recovery by suction to forcibly exhaust ink from the discharging ports by generating a given suction force on the discharging port formation face by use of a pump while forming a closed system in the ink discharging unit using a capping member as a method of recovering from the clogging condition caused by the increased viscosity of ink resulting from ink dehydration at the discharging ports, clogging brought about by ink sticking or bubbles and dust produced in the liquid path. Nevertheless, if this suction recovery is performed, there occurs a state where ink remains in the contacting portion between the discharging port formation face and the capping member. (Hereinafter ink thus remaining is referred to as "cap marking ink"). Therefore, the structure is so arranged that this cap marking ink can also be cleaned off together with the ink mist and foreign substances by rubbing the discharging port formation face with the aforesaid cleaning member.
For example, as shown in FIG. 1, there has been proposed an apparatus wherein a cleaning member comprising a plastic board is arranged at the side of a capping member between the home position of a recording head and the recording area to clean the discharging port formation face of the recording head. Also, as shown in FIG. 2, there has been proposed an apparatus wherein a cleaning member comprising two cleaning members mounted in parallel thereon is arranged, each member having a different cleaning characteristic such as different hardness or different amount of contacting depth, which generates different contact pressure against the discharging port formation face.
From the viewpoint of a simpler manufacturing process and lower manufacturing cost, recording heads having a discharging port formation face which is not flat have been proposed in recent years.
The discharging port formation face which is not flat makes it impossible for the cleaning members constructed as shown in FIG. 1 and FIG. 2 to clean the vicinity of the discharging ports sufficiently in some cases. For example, as shown in FIG. 3 and FIG. 4, while recording head 21 is structured in such a manner that a front plate is arranged in the circumference of discharging ports 21a to constitute the discharging port formation face, the portion of discharging ports 21a forms a concavity which is sunken from the plane of the cap contacting portion 21b. In the aforesaid portion of discharging ports 21a, ink droplets (including foreign substances) Y.sub.2 remain, and on the aforesaid cap contacting portion 21b, cap marking ink Z.sub.2 remain. In this condition, when recording head 21 is transported in the direction indicated by arrow A to be in contact with rubber blade 22, the cleaning of the discharging port formation face is performed.
As shown in FIG. 4, however, whereas cap marking ink Z.sub.2 is cleaned off by rubber blade 22 as recording head 21 is being transported in the direction indicated by arrow A in this example, ink droplets (including foreign substances) Y.sub.2 in the portion of discharging ports 21a remain uncleaned because these are not in contact with rubber blade 22 due to the concavity formed in the portion of discharging ports 21a.
As the above describes, in the case where the recording head is structured with a step presenting the different planes for the region in which the discharging ports are formed and the regions other than that region, it is difficult to perform a complete cleaning over the entire region of the discharging port formation face.